This invention concerns ultraviolet (UV or black) lights of a type used by technicians in carrying out leak detection inspections by illuminating potential leak sites to detect the presence fluorescent tracer dyes. This is commonly done in servicing air conditioning refrigeration systems, automobile air conditioning systems components, hydraulic machinery, etc.
The dyes are typically mixed with a compatible oil and injected into the system. If leaks are present, a trace of the dye and oil mixture flow onto external surfaces. This leakage fluoresces when illuminated with UV and sometimes blue light, emitting visible light which can be seen by the technician.
Such UV lights particularly adapted for leak detection service applications have been developed in recent years, utilizing selective reflection filters, sometimes referred to as xe2x80x9cdichroicxe2x80x9d filters which transmit ultraviolet wavelengths and reflect back visible light to maximize the user""s ability to see any fluorescence that occurs. Such lights require high wattage lamps as a UV source as compared with most other application of UV lights, which therefore emit considerable heat energy. The use of reflecting or xe2x80x9cdichroicxe2x80x9d filters is a significant improvement over absorbent filters used in the past selectively which absorbed visible light from the high intensity light emitted by the lamps, since the filters themselves overheated if the light was used for long periods and sometimes cracked during such use.
For this reason, the dichroic filters have been designed to transmit infrared radiation as well as UV to prevent overheating of the dichroic filter and other components. This is described in copending U.S. application Ser. No. 08/964,839, filed on Nov. 5, 1997 and U.S. Pat. No. 5,905,268. In those lights, visible light is reflected back into the housing such that some heating of the interior of the light occurs.
In another types of testing, dyed smoke is used to initially locate leak, requiring a flashlight to detect the smoke. Also, it is often useful to have a flashlight available in darkened locations in buildings where equipment is being serviced. The previously UV lights have not been able to be used as an ordinary flashlight.
Accordingly, it is the object of the present invention to provide a UV light which while utilizing a high intensity lamp as a powerful source of UV light does not result in overheating of the light nor specifically the optical components eliminating visible light, and which emits a very high proportion of the UV light generated by the lamp.
It is another object to provide such a UV light which is also conveniently useable as a flashlight.
The above objects as well as others which will become apparent upon a reading of the following specification and claims are achieved by using a reflector rather than a dichroic filter to selectively act to produce a beam of UV light while also directing the visible and IR radiation out from the light.
The reflector selectively reflects only emitted UV light by the lamp, while transmitting visible and IR radiation. Such dichroic reflector is commonly known in the art as a xe2x80x9ccold mirrorxe2x80x9d. The cold mirror reflector is angled with respect to the high wattage lamp so that the UV light beam is directed out of a light housing through a first window formed on one side of the light.
On the other hand, visible and infrared light is transmitted through the cold mirror reflector and out from a second window in the front end of the light housing.
A detachable cap may be secured over the second housing wind to optionally block the visible-infrared light beam from exiting the light housing.
Heating of the cold mirror reflector is minimized as none of the wavelengths are absorbed by that optical element, nor is retained elsewhere within the light housing when the cap is removed.
At the same time, the light is capable of a dual use, i.e., as a pure UV light source and also as a flashlight increasing its utility to the user, particularly where tracer smoke testing is to be practiced.
The light according to the invention is also compact and may be manufactured at low cost.